This invention relates to new 4-amino-2-(1-aryloxy-ethyl)phenol compounds and compositions containing these compounds as primary intermediates for oxidative coloring of hair fibers.
Coloration of hair is a procedure practiced from antiquity employing a variety of means. In modern times, the method most extensively to color hair is an oxidative dyeing process utilizing one or more oxidative hair coloring agents in combination with one or more oxidizing agents.
Most commonly a peroxy oxidizing agent is used in combination with one or more oxidative hair coloring agents, generally small molecules capable of diffusing into hair and comprising one or more primary intermediates and one or more couplers. In this procedure, a peroxide material, such as hydrogen peroxide, is employed to activate the small molecules of primary intermediates so that they react with couplers to form larger sized compounds in the hair shaft to color the hair in a variety of shades and colors.
A wide variety of primary intermediates and couplers have been employed in such oxidative hair coloring systems and compositions. Among the primary intermediates employed there may be mentioned p-phenylenediamine, p-toluenediamine, p-aminophenol, 4-amino-3-methylphenol, N,N-bis(2-hydroxyethyl)-p-phenylene diamine, 1-(2-hydroxyethyl)-4,5-diaminopyrazole and as couplers there may be mentioned resorcinol, 2-methylresorcinol, 3-aminophenol, 2,4-diaminophenoxyethanol, and 5-amino-2-methylphenol.
There are numerous additional requirements for oxidation dye compounds that are used to dye human hair besides the color or the desired intensity. Thus, the dye compounds must be unobjectionable in regard to toxicological and dermatological properties and must provide the desired hair color with a good light fastness, fastness to a permanent wave treatment, acid fastness and fastness to rubbing. The color of the hair dyed with the dye compounds in each case must be stable for at least 4 to 6 weeks to light, rubbing and chemical agents. Furthermore, an additional requirement is the production of a broad palette of different color shades using different developer and coupler substances. Many of the desired shades have been produced with dyes based on p-aminophenol. However, as indicated in U.S. Pat. No. 4,997,451, the use of p-aminophenol is being questioned for possible toxicological reasons. The proposed replacements for p-aminophenol have not proved entirely satisfactory. There is therefore a need for new primary intermediate compounds to meet one or more of the desired properties but not possessing the possible toxicological drawbacks possessed by p-aminophenol.
It is therefore an object of this invention to provide new primary intermediate compounds useful in place of p-aminophenol to provide a wide range of different color shades with various combinations of primary intermediates and couplers, but which do not have the toxicological drawbacks possessed by p-aminophenol.
It has been discovered that new 4-amino-2-(1-aryloxy-ethyl)phenol compounds are suitable primary intermediates for hair coloring compositions and systems for providing good oxidative coloration of hair and for providing acceptable light fastness, good selectivity, fastness to shampooing, fastness to perspiration and permanent wave treatment, and suitable for providing a wide variety of different color shades with various primary intermediate and coupler compounds.
The invention provides new 4-amino-2-(1-aryloxy-ethyl)phenol compounds of Formula (1): 
wherein R is hydrogen, hydroxy, nitro, amino, halogen, C1 to C5 alkyl or haloalkyl, C1 to C5 alkoxy or cyclic alkoxy, C1 to C5 hydroxyalkyl and C1 to C5 hydroxyalkoxy; Ar is an aromatic group, preferably an aromatic group selected from a furanyl, 2- or 3-thienyl, pyridinyl, phenyl, 2,3-dihydro-benzo[1,4]dioxin-5 or -6-yl or benzo[1,3]dioxol-4 or -5-yl group; and y =1 to 3. The halogen may be fluorine, chlorine, bromine or iodine, preferable fluorine or chlorine.
These novel primary intermediates are used to provide coloration to hair in which there is good dye uptake by the hair and provides shades or colors which are stable over a relatively long period of time. The novel primary intermediates provide for dyeing of hair to impart color or shades that possess good wash fastness and do not undergo significant changes on exposure to light or shampooing.
Preferred 4-amino-2-(1-aryloxy-ethyl)phenol compounds of this invention are those of formula (1) 
wherein R is hydrogen, amino or C1 to C3 alkyl, and Ar is phenyl, pyridinyl, furanyl, 2- or 3-thienyl, 2,3-dihydro-benzo[1,4]dioxin-5 or -6-yl or benzo[1,3]dioxol-4 or -5-yl.
The compounds of formula (1) can be prepared by the following reaction procedure where R, Ar and y are as defined hereinbefore: 
In this synthesis the new 4-amino-2-(1-aryloxy-ethyl)-phenol compounds of formula (1) of this invention can be prepared by the hydrolysis of 5-butylamido-2-hydroxyacetophenone of formula (2) with methanolic HCl to produce a compound of formula (3), then protecting the hydroxyl and amino groups of the formula (3) compound by treatment thereof with di-tert-butyl dicarbonate [(Boc)2O] to give a compound of formula (4) followed by reduction of the formula (4) compound with a reducing agent such as sodium borohydride (NaBH4) to produce a compound of formula (5) which is subjected to the Mitsunobu reaction with a reagent of the formula HOxe2x80x94Arxe2x80x94(R)y in the presence of triphenyl phosphine and diethyl azodicarboxylate or diisopropyl azodicarboxylate to produce a compound of formula (6), which is deprotected with methanolic HCl to produce a compound of formula (1).